docs: def get_replacement_types(titles, reportnumbers, publishers):
      """Given the indices of the titles and reportnumbers that have been
         recognised within a reference line, create a dictionary keyed by
         the replacement position in the line, where the value for each
         key is a string describing the type of item replaced at that
         position in the line.
         The description strings are:
             'title'        - indicating that the replacement is a
                              periodical title
             'reportnumber' - indicating that the replacement is a
                              preprint report number.
         @param titles: (list) of locations in the string at which
          periodical titles were found.
         @param reportnumbers: (list) of locations in the string at which
          reportnumbers were found.
         @return: (dictionary) of replacement types at various locations
          within the string.
      """
      rep_types = {}
      for item_idx in titles:
          rep_types[item_idx] = "journal"
      for item_idx in reportnumbers:
          rep_types[item_idx] = "reportnumber"
      for item_idx in publishers:
          rep_types[item_idx] = "publisher"
      return rep_types